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The application of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is presented for the determination of five sulfonated azo dyes in chili powders. To circumvent problems related to spectral noise and overall poor precision, acid red 88 was used as internal standard and sample cleanup was performed via ion pairing of anionic species with benzyltributylammonium bromide (BTAB) and extraction into chloroform. The key parameters influencing analytical performance were BTAB concentration, pH of the aqueous phase, amount of sample and deposition technique, concentration of 9-aminoacridine (chemical matrix), number of instant spectra per laser shot, and the raster of laser movement. The highest sample load corresponded to 100 μL of water/methanol extract taken for extraction and the method quantification limits for sunset yellow (Y6), ponceau 2R (R5), allura red (R40), and amaranth (R2) were within the range 1.50–3.10 μg g−1 (29.0 μg g−1 for tartrazine, Y5). Two-point standard addition performed in three samples yielded percentage recoveries in the range 86.4–115%; the quantification results were consistent with those obtained by HPLC-DAD. Twelve chili powders were analyzed and the results for nine of them disagreed with information provided by the manufacturers; R40 was determined in seven products at concentrations from 32.5 ± 2.1 μg g−1 to 1125 ± 73 μg g−1; Y6 and Y5 were found at lower concentrations and in fewer samples. The MALDI-TOF MS procedure can be recommended for routine control of sulfonated azo dyes in food products as a memory-free, procedurally simple, high-throughput procedure with minimal costs of instrument operation.

Carbon as an adsorbent has been widely studied for wastewater treatment, but the regeneration of adsorbent has been scarcely reported. In this paper, an economical and environmental method was applied to regenerate carbon (XC-72). Results showed that both anhydrous ethanol and deionized water did not obtain optimal effect for the desorption of Acid Orange 7, Ponceau 2R and Rhodamine B, but the desorption effect was dramatically improved when anhydrous ethanol and deionized water were mixed in a certain volume ratio. In addition, the adsorption kinetics of the three dyes were investigated, which showed that the process of adsorption could be well represented by the pseudo-second-order model. For the study of competitive adsorption, this indicated that the interaction between adsorbent and adsorbate had something to do with electrostatic attraction.

Sixty-three local white-rot fungi were isolated from soil and wood samples on potato dextrose agar (PDA). All these isolates were screened for their ability to degrade 4 textile azo dyes;Ponceau 2R (C.I. 16450), Orange G (C.I. 16230), Direct Blue 71 (C.I. 34140) and Biebrich Scarlet (C.I. 26905). Out of 40 isolates that gave positive results, only 1 promising isolate which completely degrades all 4 dyes in the minimum amount of time was selected for further investigation. This isolate was sourced from University Putra Malaysia (UPM) Serdang campus.The isolate was tentatively identified as Coriolopsis sp. Strain arf5 based on the analysis of the internal transcribed spacer (ITS) region. Nutritional studies on defined solid medium showed that this isolate was only able to degrade the 4 azo dyes under nitrogen-limiting conditions and an additional carbon source (glucose) need to be added to provide sufficient energy for the degradation to occur. Various parameters were optimized.

We employed the complete active space self-consistent field (CASSCF) and its multistate second-order perturbation (MS-CASPT2) methods to explore the photochemical mechanism of 2-hydroxyazobenzene, the molecular scaffold of Sudan I and Orange II dyes. It was found that the excited-state intramolecular proton transfer (ESIPT) along the bright diabatic (1) ππ* state is barrierless and ultrafast. Along this diabatic (1) ππ* relaxation path, the system can jump to the dark (1) nπ* state via the (1) ππ*/(1) nπ* crossing point. However, ESIPT in this dark state is largely inhibited owing to a sizeable barrier. We also found two deactivation channels that decay (1) ππ* keto and (1) nπ* enol species to the ground state via two energetically accessible S1 /S0 conical intersections. Finally, we encountered an interesting phenomenon in the excited-state hydrogen-bonding strength: it is reinforced in the (1) ππ* state, whereas it is reduced in the (1) nπ* state. The present work sets the stage for understanding the photophysics and photochemistry of Sudan I-IV, Orange II, Ponceau 2R, Ponceau 4R, and azo violet.

In this paper, alcohol (methanol, ethanol, n-propanol)-water system was used as solution for the desorption of Acid Orange 7 (AO7), Ponceau 2R and Rhodamine B (RhB) from dye-loaded carbon (XC-72). Excellent degradation efficiency was obtained (desorption efficiency reaches 77.35%, 85.60%, 96.86% for Ponceau 2R, AO7 and Rhodamine B, respectively) and it was significantly influenced by alcohol content and the length of carbon chain in alcohol (hydrophobicity). In addition, desorption kinetics was fitted by a second-order desorption model, and the desorbed quantity at equilibrium (qe) and rate constant (kd) were calculated, respectively.

A high-performance capillary electrophoresis (HPCE) method for simultaneous determination of nine banned azo dyes including orange 2 sodium salt, ponceau SX, ponceau 2R, metanil yellow, yellow 2G, ponceau 3R, naphthol orange, acid violet 7, and acid yellow 11 in foodstuffs and beverages was established. After being extracted with methanol and cleaned up with Proelut PWA column, the separation of the target azo dyes in sample solution was performed in an uncoated fused-silica capillary (60 cm × 75 μm I.D.) with an effective length of 50 cm. The running buffer consisted of 15 % acetonitrile-10-mM borate buffer (pH = 9.0), and the applied voltage was 25 kV with the separation temperature of 25 °C. The calibration curves of the method were linear in the range of 0.50–100.0 μg/ml with correlation coefficients greater than 0.999. The recoveries of the method ranged from 81.2 to 110 %. The limits of detection (LODs) and the quantification of the method were in the ranges of 25.1–75.1 μg/l and 0.083–0.25 mg/kg, respectively. The relative standard deviations (RSDs) of interday and intraday were in the ranges of 1.90 to 5.81 % and 0.12 to 3.42 %, respectively. This method has been successfully applied to the simultaneous determination of aforementioned nine azo dyes in foodstuffs and beverages.

The wettability of plant leaf surface reflects the hydrophilic ability of leaves, and influences the spreading and retention behavior of liquid on leaf surface directly, which resulted in the affection of droplet deposition effect as well. In this study, contact angle was used to characterise leaf surface wettability, the influence of vegetable oil addition on leaf surface wettability and droplet deposition effect was investigated, and the correlation models between leaf surface wettability and deposition amount were established. Besides, the photolysis rate and elution recovery rate of tartrazine 85, allura red, ponceau 2R and methylene blue were compared. As a result, with the increase of vegetable oil addition in spray indicator, the contact angles of spray indicator on rape leaf surface decreased sharply at first, then slowly and tended to be stable, while the deposition amount showed a trend of sharp rise and then fluctuated in a certain range. Meanwhile, the droplet deposition amount on rape leaves was positively correlated with surface wettability, the correlation from good to bad was: tartrazine 85 (R = 0.9299), allura red (R = 0.9244), ponceau 2R (R = 0.9202), methylene blue (R = 0.8748). In combination with the photolysis rate and elution recovery rate of four spray indicators, tartrazine 85 and allura red performed better than ponceau 2R and methylene blue for their low photolysis rate and high elution recovery rate, which were more suitable for farmland spray applications.

Synthetic dyes are added to food and drinks to restore their original appearance when color is affected by processing, storage, packaging and distribution. Furthermore colors are used to make food more visually attractive to consumers. The EU Directive 1994/36/CE lists the permitted substances that can be used in foodstuffs. In order to investigate the content of some permitted and non-permitted dyes in food and drinks, a sensitive and helpful method has been developed to determine simultaneously seventeen synthetic colorants by high-performance liquid chromatography coupled with a diode-array detector in solid food matrices and beverages. Substances involved were azorubine (E122), amaranth (E123), cochineal red A (E124), red 2G (E128), allura red (E129), azocarmine B (AZO B), azocarmine G (AZO G), ponceau 2R (P2R), ponceau 6R (P6R), tartrazine (E102), sunset yellow (E110), quinoline yellow (E104), orange II (OR II), metanil yellow (MY), patent blue V (E131), indigo carmine (E132) and brilliant blue FCF (E133). Solid food matrices were extracted by a water–alcohol mixture, cleaned up on a polyamide SPE cartridge and eluted with basic methanol solution. Otherwise a simple dilution and filtration of samples were used for drinks. The method has been validated according to Regulation (2004/882/CE) and could be applied to a concentration range between 5 and 300 mg kg−1 (5–100 mg l−1 for drinks) depending on the dye. The accuracy (precision and trueness) and specificity were assessed. During years 2009–2011 many food samples for the detection of synthetic colorants were analyzed. Most of them were fresh fishery products in which the use of food colorant is banned.

We report for the first time a novel and rapid (1 h) synthesis method for birnessite-type MnO2 nanostructures via a polyol-reflux process through oxidizing MnCl2 with H2O2 under basic conditions in the presence of polyvinylpyrrolidone (PVP). Influencing factors such as the dosage of reactants and the reaction times are systematically investigated. The molar ratios of OH/Mn played an important role in the formation of birnessite-type MnO2 nanostructure with good crystallinity and ordered 3D nanostructures. A possible formation mechanism for the nanostructure was proposed. The flower-like birnessite-type MnO2 nanostructure is composed of nanosheets with an average diameter ca. 300–500 nm and shows mesoporous characteristics with a pore diameter of 20 nm. Due to its unique mesoporous structure, the birnessite-type MnO2 exhibits excellent ability to remove organic pollutants (Ponceau 2R) and shows a potential application as an electrochemical capacitor.

Luminescent solar concentrators (LSCs) with styrene (ST) and methylmethacrylate (MMA) of different percentage as the matrix were prepared by a casting method using ponceau 2R. DSC has been used to compare the thermal stability of the different LSCs. FTIR spectroscopy shows that appearance of -N=N- for ponceau 2R in all ST/MMA matrixes indicating that the highest stability of this kind of dye in these matrixes. The values of the optical band gap (Eg) have been obtained from direct allowed transition before and after the samples have been exposed to sunlight for 9 weeks. Photodegradation studies revealed that the more photostable dye doped in PMMA matrix than in other matrixes. The results showed that the homo PMMA/ponceau 2R system has the highest fluorescence quantum yield (Qf). Therefore this sample can be selected for field performance of fluorescent solar collectors. The photovoltaic cell coupled with homo PMMA/2R LSC shows a maximum efficiency, 2% compared to the normal one.

Native polyacrylamide electrophoresis in the presence of two reversible protein anionic stains (Ponceau S and Ponceau 2R) was used to study the oligomeric states of soluble proteins. A mild binding of the used protein stains to nondissociated protein oligomers imposed a charge shift on the proteins resulting into separation of protein species according to their size under physiological conditions. Adsorbed stains could be easily removed after electrophoresis by washing of polyacrylamide gel with buffer and protein complexes could be visualized either by the detection of their enzyme activity or by using a nonspecific protein stain. The specific detection of enzyme activity of glycosidases, lactate dehydrogenase, or phosphatases was shown as an example.

Problem statement: Current researches had shown that the photostability of a luminescent solar collector depend on the method of its preparation and type of using dye. This research therefore aimed at studying the stability of luminescent solar collector prepared by sol-gel spin coating method using Ponceau 2R. Approach: The effect of silica matrix on the photostability and fluorescence properties of Ponceau 2R was investigated in terms of concentration using absorption and emission techniques. The photostability of Ponceau 2R doped sol-gel samples was also examined through 60 days exposure to sunlight. Results: The dye in the solid matrix had absorption and emission characteristics different from those in the liquid solution. The transition energy for electrons were direct allowed transition for all examined concentrations and there is no variation in the values of optical gap Energy (Eg) by increasing the dye content or exposure times. The dependence of the width of the tails of the localized states in the band gap (Eu) on the concentration and exposure times were also studied. The emission spectra for the samples before and after exposure to sunlight showed that the sample of concentration 0.1 wt% had the highest fluorescent intensity and fluorescence quantum yield. Conclusion/Recommendations: This study showed that Ponceau 2R of 0.1 wt% concentration has a good potential for application in a luminescent solar collector using sol-gel techniques.

A series of photocatalysts, K11[Ln(PW11O39)2]/PVA (Ln=La, Ce, Pr, Nd, Sm) were prepared by K11[Ln(PW11O39)2] (Ln=La, Ce, Pr, Nd, Sm) containing five kinds of lanthanides and polyvinyl alcohol as the support. The catalysts obtained were characterized by Fourier transform infrared spectra, UV-vis spectra, powder X-ray diffraction, and scanning electron microscopy, indicating that the structure of K11[Ln(PW11O39)2] and polyvinyl alcohol remained intact, respectively. The photocatalysts exhibited efficient catalytic activity to degrade methyl orange, Congo Red, Ponceau 2R. The maximal degradation conversions of the three kinds of dyes were 99.58%, 47.61%, 72.42%, respectively.

Stereum hirsutum, a white rot fungus, has a good growth in solid state fermentation. This was carried on with wheat bran, soy bran and a mixture of both. Mycelia grown on soy bran showed the highest decolorization activity on Ponceau 2R (xylidine), indigo carmine and malachite green. Optimal relationship between decolorization and detoxification of malachite green was 30 g of fresh weight (mycelia plus substrate) in 500 ml malachite green solution, 42 U/l of laccase was measured in this solution. Decolorization was carried on without the addition either of nutrients or mediators. Conditions for maximal decolorization did not agree with those for maximal ligninolytic enzyme production, but effectiveness of laccase activity on decolorization was evidenced by electrophoretic analysis, that allowed laccase identification and its decolorization activity in gels stained with indigo carmine and malachite green, with ABTS as mediator. Detoxification was assayed using the sensible fungus Phanerochaete chrysosporium.

Based on both capabilities of extracellular electron transfer and high salt tolerance, marine exoelectrogenic bacteria have the potential to serve as halotolerant/halophilic exoelectrogenic decolorizers (HEDs) for textile wastewater treatment. However, research in this area is still rare. In this study, we employed Shewanella marisflavi EP1 for this purpose. The results showed that EP1 could decolorize Xylidine Ponceau 2R (XP2R) under high NaCl concentrations up to 20%. Two different mechanisms were involved: degradation and bioflocculation. XP2R was decolorized by degradation in the range of 0-7.4% NaCl, by bioaugmented flocculation in 10-20% NaCl; and the range of 7.4-10% NaCl was the transition period from degradation to flocculation. Considering the property of flocculation by strain EP1, it is reasonable that XP2R was hard to penetrate into EP1 cells, thus it was an extracellular process of decolorization. The overall results further suggested that like EP1, marine exoelectrogenic bacteria might serve as a category of functional microbes (i.e., HEDs) for textile wastewater treatment.

Dyes especially azo dyes are used extensively as coloring agents in the manufacturing process of inks, textiles, leathers, food and pharmaceuticals. Liver, bacterial (anaerobic and aerobic) and fungal enzymes metabolized azo dyes immediately and released corresponding amines with carcinogenic character. Thus, the metabolism and release of amine products from azo compounds are of considerable interest. The present study emphases on the qualitative and quantitative analysis of products released from xylidine ponceau 2R by extra cellular protein (ECP) of Streptomyces sp. SS07, in comparison with the chemical reduction. It has been observed that both enzymatic and chemical catalysis release considerable quantities of similar type of amine compounds. The extra cellular fluid protein of 0.7852 mg/mg of ECP, on treatment with xylidine ponceau 2R, releases 2,4- xylidine, 2,6-xylidine and 2-methyl 3-amino p-quinone as products at pH 9.2 and at 37 °C for a contact period of 24 h. The clear band obtained in nondenaturing polyacrylamide gel electrophoresis showed the pure nature of the enzyme used for the reduction of dye xylidine ponceau 2R. Further, HPLC and GC–MS analysis of the reaction products after extracted with chloroform, revealed that about 5–20% increase in the quantity of amine was released by ECP.

A new preparative method for cross-sectioning and staining of fibrous materials was developed and the differential staining was applied to reconfirm the bilateral structure of Merino wool fibers under an optical microscope observation. A part of a cross-section (ortho-cortex) of a Merino wool fiber was stained specifically by some selected basic dyes independent of pH of the medium while only at pH 6.86 by Acid Violet. The other part of the cross-section (para-cortex) was stained by Ponceau 2R at pH 6.86 at 60°C for 1h. The mechanism of differential staining of wool fibers having bilateral structure by basic dyes and acid dyes was investigated in detail.

A quantitive assay for the determination of Xylidine Ponceau 2R was established by high performance liquid chromatography (HPLC) with solid phase extraction. Xylidine Ponceau 2R was extracted by alcohol-ammonia, solid phase extraction was utilized to cleanup. The separation was performed in a XDB-C18 column, acetonitrile, 5mmol/L ammonium acetate and 0.06% triethylamine as mobile phase. A photo-diode array detector was used to detect the compositions at 504 nm. The linear range of the method was 0.1~15 mug/mL, the limit of detection was 0.02 mg/L, the relative standard deviation was 0.33-2.86% and the average recoveries were 90.66~93.89%. The method was accuracy, sensitivity and feasibility to analyze the residues of Xylidine Ponceau 2R in foodstuffs.

Forty synthetic food colors were determined in drinks and candies by reversed-phase high-performance liquid chromatography with photodiode array detection. The following food colors were analyzed within 19 min using a short analytical column (50 mm x 4.6 mm i.d., 1.8 microm) at 50 degrees C with gradient elution: Ponceau 6R, Tartrazine, Fast yellow AB, Amaranth, Indigotine, Naphthol yellow S, Chrysoine, Ponceau 4R, Sunset yellow FCF, Red 10B, Orange G, Acid violet 7, Brilliant black PN, Allura red AC, Yellow 2G, Red 2G, Uranine, Fast red E, Green S, Ponceau 2R, Azorubine, Orange I, Quinoline yellow, Martius yellow, Ponceau SX, Ponceau 3R, Fast green FCF, Eosine, Brilliant blue FCF, Orange II, Orange RN, Acid blue 1, Erythrosine, Amido black 10B, Acid red 52, Patent blue V, Acid green 9, Phloxine B, Benzyl violet 4B, and Rose bengal. The recoveries of these compounds added to soft drinks and candies at 5 microg/g ranged from 76.6 to 115.0%, and relative standard deviations (R.S.D.s) were within 6.0%. The limits of detection and the limits of quantitation were 0.03 and 0.1 microg/g, respectively.

Although collagen of either tendon or dermis can be stained equally well with Ponceau 2R/Acid Fuchsin or Light Green SF if the dyes are used independently, tendon collagen retains the red dye mixture and dermal collagen the green counterstain when the dyes are used sequentially in the Masson trichrome procedure. The results of experiments designed to assess differences in the penetration, retention and displacement of these arylmethane dyes have demonstrated that they are retained more firmly by the tensioned collagen of tendon or stretched dermis, and are more easily displaced from the collagen of relaxed tendon or dermis.

A method is described which demonstrates nuclei, elastic fibers, red blood cells, collagen and fibrin. Nuclei and elastic fibers are stained by a modified Verhoeff's elastic tissue stain which was previously developed and used in the elastic-Masson combination. Both early fibrin and red blood cells are shown by lissamine fast yellow. Mature fibrin, some types of collagen and other cytoplasmic changes are stained by a combination of acid fuchsin, Biebrich scarlet and ponceau 2R, while old fibrin is demonstrated by the collagen stain. This method takes about 1 hr to perform and has the added advantage that several entities are clearly shown in a single slide.

Although normally, dermal collagen fails to retain the Ponceau 2R/Acid Fuchsin component of the Masson trichrome procedure and is stained green by the counterstain, the collagen of sections of human dermis which have been heated above its denaturation temperature (Ts) in moist conditions will retain the initial red stain. This difference in dye retention appears to be related to conformational changes of the collagen molecule which are associated with denaturation, for the change in staining is directly related to the shrinkage temperature, is reversed by rapid cooling after heating, is profoundly affected by differences in environmental conditions during heating which affect molecular rearrangement, and is age-dependent.

Several dyes, notably ponceau 2R, azofuchsin 3B, nitrazine yellow, and Biebrich scarlet may replace imported “ponceau de xylidin” in the Masson ponceau acid fuchsin mixture. Of these Biebrich scarlet appears to be the best and may be used without acid fuchsin.A mixture of equal parts of 5% solutions of phosphomolybdic and phosphotungstic acids is much superior to either acid alone and gives adequate mordanting in 1 minute at 22°C.With the fast green modification, times in plasma and fiber stains can be reduced to 2 minutes each. With anilin blue a 4-minute plasma stain is required. One-minute final differentiation in 1% acetic acid is adequate.Primary mordanting of formalin material may be accomplished by 5 minutes in saturated aqueous mercuric chloride or 2 minutes in saturated alcoholic picric acid. Three minutes washing in running water is required after these mordants.

The main constituents of wheat flour and many wheat flour products are wheat protein (gluten) and starch granules. The specific staining of the protein present was effected by 10 min in 0.1% aqueous ponceau 2R (C.I. No. 16150) acidified with 3—4 drops of 1 N H2SO4 per 50 ml of staining solution, followed by rinsing in 2 changes of distilled water, dehydrating, clearing and mounting in a resinous medium in the normal way. Staining of starch was as follows: sections or flour smears were brought to water, treated for 10 min in a protein-blocking reagent (Taninol ADR—Imperial Chemical Industries—used in 1% aqueous solution) rinsed, then stained for 3 mins in 0.5% aqueous chlorazol violet R (C.I. No. 32445) or for 10 min in either 0.5% aqueous chlorazol violet N (C.I. No. 22570), or chlorazol black E (C.I. No. 30235). Staining was followed by thorough rinsing, normal dehydration and clearing and mounting in a medium of R.I. about 1.49 to enhance visibility of unstained starch grains. The methods are applicable...

SUMMARY Proteins were stained (brilliant red) by using 0·5% Ponceau 2R (C.I. 16150) in sulphuric acid (pH 2) at 40°C on sections 1–2 μm thick of tissues fixed in glutaraldehyde-osmium tetroxide and embedded in epoxy resins. The staining is free from precipitates and does not require the removal of the embedding media. Section bleaching with 1–2% periodic acid at 40°C for 30–90 min was also carried out in order to obtain a more brilliant colour of the proteins which may be photographed using black and white films.

SUMMARY An aqueous solution (pH 1·5) of 0·5% Ponceau 2R (C.I. 16150) and 2% periodic acid was used at 318 K to stain proteins (brilliant red) and simultaneously to bleach the osmicated non-proteinaceous cell structures on 1–2 μm thick sections of tissues fixed in glutaraldehyde-osmium tetroxide and embedded in epoxy resins. This H5IO6 bleaching-Ponceau 2R staining procedure only stains the proteins so that black-and-white films can be used.

A SMALL drop of citrated human blood is placed on a slide next to a somewhat larger drop of Ponceau 2R and the two drops are mixed, covered with a cover glass and examined both with ordinary and polarized light. Under the double action of the dye and the hypotonicity, all the red cells become perfectly spherical with a diameter ranging from 5.0 to 5.6µ and stain weakly orange-red. No birefringence is observed.

Summary Calcium salts of acid dyes for lakes are widely used in the pigment industry, but these dyes have not yet been employed in the staining of calcium deposits. The usefulness of such dyes for light and fluorescence microscopy of calcium deposits was investigated. Human autopsy material was fixed in alcohol, Carnoy's fluid, methacarn, 10% unbuffered formalin or Zenker-formol. Deparaffinized sections were stained in 0.5% aqueous solutions of Biebrich Scarlet, Bordeaux Red B, Brilliant Black, Croceine Orange Y, Fast Light Rubine BL or Ponceau 2R for 30 minutes to one hour, rinsed in water, dehydrated and mounted. Alkali-soluble calcium deposits were stained intensely and selectively; alkali-insoluble calcium deposits remained unstained. Absolute alcohol, Carnoy's fluid and methacarn preserved calcium deposits equally well, but 10% unbuffered formalin and Zenker-formol removed alkali-soluble calcium deposits. Ponceau 2R imparted strong selective fluorescence to alkali-soluble calcium deposits. In mixed UV-blue plus green tungsten light calcium deposits were bright red; non-fluorescent tissue structures appeared green.

WOS: 000076130100016, Swollen hydrogels were prepared by gamma-radiation copolymerization of N-vinyl-2 pyrrolidone and acrylonitrile. The influence of radiation dose and feed composition on the swelling properties, diffusional behavior of water and diffusion coefficients of the hydrogel systems were examined. N-vinyl-2-pyrrolidone/acrylonitrile hydrogels were swollen in the range 50-850%. Water diffusion to the hydrogels generally was a non-Fickian type diffusion. The hydrogel were used in the studies of adsorption of some water soluble dye such as basic blue 9, tetraethyl rhodamine, xylidine ponceau 2R, indigo carmine, helianthin and erythrosine, and of a vitamin riboflavin (Vitamin B-2).

ONLY small amounts of alkaline phosphatase have hitherto been found in mammalian endocrines. It was, however, possible to demonstrate considerable quantities of this enzyme in the anterior pituitary lobe of both the male and the female guinea pig. After fixation of the glands in 96 per cent alcohol, in 80 per cent alcohol, in acetone or in pyridine-alcohol1, the Gomori technique2 was used. As already known, the nuclei of the anterior pituitary show a positive reaction which, however, has not been localized to any particular cell type3. In order to identify the type of cells containing the phosphatase, every two of four paraffin sections (thickness : 2–4μ) of each gland were examined as to content of phosphatase : the two other sections were stained by Masson‘s trichrome (acid fuchsin, Ponceau 2R and aniline blue) method.